A car body includes main parts such as an underbody, left and right side members, and a roof panel. For assembling a car body from these parts, parts to be fixed are first located to each other using locating jigs, for example. Thereafter, these parts are pre-fixed by spot welding, and then subjected to re-welding for complete fixation.
A conventional method of assembling a car body utilizes a significantly large locating jig for locating the main parts. For example, a jig used for locating the side member is larger than the side member itself. Such a locating jig is designed to be movable toward and away from the car body assembly line. After a side member is set to the locating jig, the jig is moved toward the assembly line, and fixed at a predetermined position. In this state, the side member is pre-welded to the underbody.
The above conventional locating jig is large and heavy, which causes various problems. For example, the initial facility investment tends to be large. Further, it can take a lot of trouble to change locating jigs according to a car type changed, and during the replacement the assembly line may need be completely stopped.